Windows, doors, partitions, and other structures having controllable tinting have been gaining popularity in the marketplace. These structures are commonly referred to as “smart” structures or “privacy” structures for their ability to transform from a transparent state in which a user can see through the structure to a private state in which viewing is inhibited through the structure. For example, smart windows are being used in high-end automobiles and homes and smart partitions are being used as walls in office spaces to provide controlled privacy and visual darkening.
A variety of different technologies can be used to provide controlled privacy for a smart structure. For example, electrochromic technologies, photochromic technologies, thermochromic technologies, suspended particle technologies, and liquid crystal technologies are all being used in different smart structure applications to provide controllable privacy. The technologies generally use an energy source, such as electricity, to transform from a transparent state to a privacy state or vice versa.
Regardless of the type of controlled privacy technology used for a smart structure, few if any structures block one hundred percent of directly transmitted visible light when private. Rather, even high performing technologies can still allow a small amount of direct visible transmittance through the structure when in a privacy state. This may allow an observer looking through the structure to see general shapes and motion on the opposite side of the structure. In applications where absolute privacy is not of primary importance, such as an automobile window where privacy glass is used to block sunlight and keep the interior of the automobile cool, residual transmittance is generally not of concern. On the other hand, for residential window and door applications, consumers generally desire absolute privacy when their windows and doors are in a privacy state. This is particularly true at night when illumination from the interior of a home can provide backlighting that helps highlight structures behind a privacy darkened window or door to an outside observer.